1. Field of the Invention
The present invention relates to an ink jet recording apparatus and to an ink jet recording method for recording an image. More specifically, the present invention relates to an on-demand type ink jet recording apparatus using an on-demand type ink jet recording method of forming one pixel having a plurality of ink droplets.
2. Description of the Related Art
Recently, as information processing systems using personal computers and the like have come into wide use, image information handled thereby is diversified. From this point of view, recording apparatuses for outputting the image information from the information processing systems are required to make various types of output. So-called high definition recording is one of the various types of output.
When the high definition recording is effected by ink jet recording systems, it is customary to employ a method of discharging or ejecting ink droplets as fine liquid droplets.
However, an increase of ink density due to the evaporation of volatile components contained in the ink is a relatively important problem with apparatuses which record by discharging fine ink droplets.
More specifically, on-demand type ink jet recording heads which are used by almost all of the ink jet recording apparatuses have discharge ports from which ink is not always continuously discharged. When ink is not continuously discharged, the density of coloring material within the ink may be increased in the vicinity of the ink discharge ports from which no ink was recently discharged because volatile components, such as water and the like, in the ink are evaporated from the ink discharge ports. When discharge of the ink is resumed, almost all of the small droplets of the ink have a relatively high concentration of color material, and a dot made of the ink droplets has a color density higher than that of other dots. In this case, it is possible that the portion of a recording image where the discharge of the ink is resumed as described above, or the portion to which discharge of the ink is newly started (hereinafter, referred to as a writing start position), has a relatively high color density.
This problem is particularly noticeable in recording systems such as the so-called multi-pass system and the multi-scan system in which one line in a main scanning direction is formed by being scanned a plurality of times. The problem occurs because if a plurality of different discharge ports record onto one line, ink droplets which were condensed at the respective discharge ports while the discharge of the ink therefrom was earlier presented are discharged to the same writing start position during a plurality of scans. As a result, the density of the image at the writing start position is relatively high and conspicuous.